rubeola vs rubella

rubeola and rubella both are nouns.

Word	Noun	Adjective	Verb	Adverb
rubeola	Yes	No	No	No
rubella	Yes	No	No	No

As nouns, rubella is a hyponym of rubeola; that is, rubella is a word with a more specific, narrower meaning than rubeola:

rubeola: an acute and highly contagious viral disease marked by distinct red spots followed by a rash; occurs primarily in children
rubella: a contagious viral disease that is a milder form of measles lasting three or four days; can be damaging to a fetus during the first trimester

Other hyponyms of rubeola include epidemic roseola, German measles, three-day measles.

rubeola (noun)	rubella (noun)
an acute and highly contagious viral disease marked by distinct red spots followed by a rash; occurs primarily in children	a contagious viral disease that is a milder form of measles lasting three or four days; can be damaging to a fetus during the first trimester